The invention relates to center pivot irrigation systems of the type wherein a long water distribution pipe is supported by a plurality of wheeled towers for rotation over the ground and around a central pivot point to which the main distribution pipe is attached and from which the irrigation water is supplied. More specifically, the invention concerns the construction of the pivot point swivel pipe assembly and the appropriate supports therefor.
Swivel pipe assemblies have, for the most part, consisted of a vertical or upright pipe section rotatably coupled to an upper elbow or "goose neck" which is attached to the main distribution pipe. The upright pipe was typically supported by a pyramidal steel structure, the apex of which was just below the upper elbow and the four corners of which were fastened to concrete piers buried in the ground. As the center pivot irrigation art advanced, system designs incorporated higher and higher structures for supporting the main distribution pipe which required higher and larger pyramidal pivot point supporting structures. Not only did these pivot structures require greater physical dimensions, they had to be constructed so as to resist greater bending moments because the lateral pull on the swivel pipe was being exerted at a greater distance from the ground.